docs: def sequence_path(self, fasta_path):
          """Provide pointers to the paths of the FASTA file
  
          Args:
              fasta_path: Path to FASTA file
  
          """
          if not fasta_path:
              self.sequence_dir = None
              self.sequence_file = None
  
          else:
              if not op.exists(fasta_path):
                  raise OSError('{}: file does not exist'.format(fasta_path))
  
              if not op.dirname(fasta_path):
                  self.sequence_dir = '.'
              else:
                  self.sequence_dir = op.dirname(fasta_path)
              self.sequence_file = op.basename(fasta_path)
  
              tmp_sr = SeqIO.read(fasta_path, 'fasta')
              if self.name == '<unknown name>':
                  self.name = tmp_sr.name
              if self.description == '<unknown description>':
                  self.description = tmp_sr.description
              if not self.dbxrefs:
                  self.dbxrefs = tmp_sr.dbxrefs
              if not self.features:
                  self.features = tmp_sr.features
              if not self.annotations:
                  self.annotations = tmp_sr.annotations
              if not self.letter_annotations:
                  self.letter_annotations = tmp_sr.letter_annotations